//
//  OfflineCollectionRegistrationViewController.swift
//  suixinkan
//

import SnapKit
import UIKit

/// 线下收款登记页，仅收集金额和线下收款方式。
final class OfflineCollectionRegistrationViewController: BaseViewController {
    private let viewModel: OfflineCollectionRegistrationViewModel

    private let scrollView = UIScrollView()
    private let contentStack = UIStackView()
    private let amountCard = UIView()
    private let amountField = UITextField()
    private let methodCard = UIView()
    private let methodStack = UIStackView()
    private var methodButtons: [OfflineCollectionPaymentMethod: OfflinePaymentMethodButton] = [:]
    private let explanationCard = UIView()
    private let contextLabel = UILabel()
    private let bottomContainer = UIView()
    private let submitButton = UIButton(type: .system)
    private var hasFocusedAmountField = false

    /// 使用指定的收款上下文与 Mock 服务创建登记页。
    init(
        context: OfflineCollectionContext = .current(),
        service: OfflineCollectionMockService = .shared
    ) {
        viewModel = OfflineCollectionRegistrationViewModel(context: context, service: service)
        super.init(nibName: nil, bundle: nil)
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func setupNavigationBar() {
        title = "线下收款登记"
    }

    override func setupUI() {
        view.backgroundColor = AppColor.pageBackground
        scrollView.keyboardDismissMode = .interactive
        scrollView.alwaysBounceVertical = true
        contentStack.axis = .vertical
        contentStack.spacing = AppSpacing.md

        configureCard(amountCard)
        let amountTitleLabel = makeTitleLabel("收款金额")
        let currencyLabel = UILabel()
        currencyLabel.text = "¥"
        currencyLabel.font = .systemFont(ofSize: 34, weight: .semibold)
        currencyLabel.textColor = AppColor.textPrimary

        amountField.placeholder = "0.00"
        amountField.font = .systemFont(ofSize: 38, weight: .bold)
        amountField.textColor = AppColor.textPrimary
        amountField.keyboardType = .decimalPad
        amountField.clearButtonMode = .whileEditing
        amountField.delegate = self
        amountField.accessibilityLabel = "收款金额"

        let amountHelperLabel = UILabel()
        amountHelperLabel.text = "单笔金额 0.01～99,999.99 元，最多两位小数"
        amountHelperLabel.font = .systemFont(ofSize: 12)
        amountHelperLabel.textColor = AppColor.textTertiary

        let amountRow = UIStackView(arrangedSubviews: [currencyLabel, amountField])
        amountRow.axis = .horizontal
        amountRow.alignment = .center
        amountRow.spacing = AppSpacing.sm
        let amountStack = UIStackView(arrangedSubviews: [amountTitleLabel, amountRow, amountHelperLabel])
        amountStack.axis = .vertical
        amountStack.spacing = AppSpacing.sm
        amountCard.addSubview(amountStack)
        amountStack.snp.makeConstraints { make in
            make.edges.equalToSuperview().inset(AppSpacing.lg)
        }
        amountField.snp.makeConstraints { make in
            make.height.equalTo(58)
        }

        configureCard(methodCard)
        let methodTitleLabel = makeTitleLabel("收款方式")
        methodStack.axis = .horizontal
        methodStack.distribution = .fillEqually
        methodStack.spacing = AppSpacing.sm
        for method in OfflineCollectionPaymentMethod.allCases {
            let button = OfflinePaymentMethodButton(method: method)
            button.addTarget(self, action: #selector(methodTapped(_:)), for: .touchUpInside)
            methodButtons[method] = button
            methodStack.addArrangedSubview(button)
        }
        let methodContentStack = UIStackView(arrangedSubviews: [methodTitleLabel, methodStack])
        methodContentStack.axis = .vertical
        methodContentStack.spacing = AppSpacing.md
        methodCard.addSubview(methodContentStack)
        methodContentStack.snp.makeConstraints { make in
            make.edges.equalToSuperview().inset(AppSpacing.lg)
        }
        methodStack.snp.makeConstraints { make in
            make.height.equalTo(64)
        }

        configureCard(explanationCard)
        let explanationIcon = UIImageView(image: UIImage(systemName: "info.circle.fill"))
        explanationIcon.tintColor = AppColor.primary
        explanationIcon.contentMode = .scaleAspectFit
        let explanationLabel = UILabel()
        explanationLabel.text = "登记后将计入今日待补缴，不生成订单。"
        explanationLabel.font = .systemFont(ofSize: 14)
        explanationLabel.textColor = AppColor.textSecondary
        explanationLabel.numberOfLines = 0
        explanationCard.addSubview(explanationIcon)
        explanationCard.addSubview(explanationLabel)
        explanationIcon.snp.makeConstraints { make in
            make.leading.top.equalToSuperview().inset(AppSpacing.md)
            make.width.height.equalTo(20)
        }
        explanationLabel.snp.makeConstraints { make in
            make.leading.equalTo(explanationIcon.snp.trailing).offset(AppSpacing.sm)
            make.trailing.bottom.equalToSuperview().inset(AppSpacing.md)
            make.top.equalToSuperview().inset(AppSpacing.md)
        }

        contextLabel.text = "当前：\(viewModel.context.collectorName) · \(viewModel.context.storeName) · \(viewModel.context.scenicName)"
        contextLabel.font = .systemFont(ofSize: 12)
        contextLabel.textColor = AppColor.textTertiary
        contextLabel.numberOfLines = 0
        contextLabel.textAlignment = .center

        bottomContainer.backgroundColor = .white
        bottomContainer.layer.shadowColor = UIColor.black.cgColor
        bottomContainer.layer.shadowOpacity = 0.06
        bottomContainer.layer.shadowRadius = 8
        bottomContainer.layer.shadowOffset = CGSize(width: 0, height: -2)

        var submitConfiguration = UIButton.Configuration.filled()
        submitConfiguration.title = "确认登记"
        submitConfiguration.baseBackgroundColor = AppColor.primary
        submitConfiguration.baseForegroundColor = .white
        submitConfiguration.cornerStyle = .medium
        submitConfiguration.titleTextAttributesTransformer = UIConfigurationTextAttributesTransformer { incoming in
            var outgoing = incoming
            outgoing.font = .systemFont(ofSize: 17, weight: .semibold)
            return outgoing
        }
        submitButton.configuration = submitConfiguration
        submitButton.accessibilityIdentifier = "offlineCollection.submit"

        view.addSubview(scrollView)
        scrollView.addSubview(contentStack)
        [amountCard, methodCard, explanationCard, contextLabel].forEach(contentStack.addArrangedSubview)
        view.addSubview(bottomContainer)
        bottomContainer.addSubview(submitButton)
    }

    override func setupConstraints() {
        bottomContainer.snp.makeConstraints { make in
            make.leading.trailing.equalToSuperview()
            make.bottom.equalTo(view.keyboardLayoutGuide.snp.top)
        }
        submitButton.snp.makeConstraints { make in
            make.top.equalToSuperview().inset(AppSpacing.md)
            make.leading.trailing.equalToSuperview().inset(AppSpacing.screenHorizontalInset)
            make.height.equalTo(50)
            make.bottom.equalToSuperview().inset(AppSpacing.md)
        }
        scrollView.snp.makeConstraints { make in
            make.top.leading.trailing.equalTo(view.safeAreaLayoutGuide)
            make.bottom.equalTo(bottomContainer.snp.top)
        }
        contentStack.snp.makeConstraints { make in
            make.edges.equalToSuperview().inset(AppSpacing.screenHorizontalInset)
            make.width.equalTo(scrollView.snp.width).offset(-AppSpacing.screenHorizontalInset * 2)
        }
    }

    override func bindActions() {
        amountField.addTarget(self, action: #selector(amountChanged), for: .editingChanged)
        submitButton.addTarget(self, action: #selector(submitTapped), for: .touchUpInside)

        viewModel.onStateChange = { [weak self] in
            Task { @MainActor in self?.applyViewModel() }
        }
        viewModel.onShowMessage = { [weak self] message in
            Task { @MainActor in self?.showToast(message) }
        }
        viewModel.onRegistrationSuccess = { [weak self] receipt in
            Task { @MainActor in self?.showRegistrationSuccess(receipt) }
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        applyViewModel()
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        guard !hasFocusedAmountField else { return }
        hasFocusedAmountField = true
        amountField.becomeFirstResponder()
    }

    @MainActor
    private func applyViewModel() {
        if amountField.text != viewModel.amountText {
            amountField.text = viewModel.amountText
        }
        methodButtons.forEach { method, button in
            button.setSelected(method == viewModel.paymentMethod)
        }
        submitButton.isEnabled = viewModel.canSubmit
        submitButton.configuration?.showsActivityIndicator = viewModel.isSubmitting
        submitButton.configuration?.title = viewModel.isSubmitting ? "登记中" : "确认登记"
        submitButton.alpha = submitButton.isEnabled || viewModel.isSubmitting ? 1 : 0.45
    }

    @MainActor
    private func showRegistrationSuccess(_ receipt: OfflineCollectionRegistrationReceipt) {
        amountField.resignFirstResponder()
        let message = """
        本次登记 \(OfflineCollectionMoney.display(receipt.record.amountFen))
        今日累计线下收款 \(OfflineCollectionMoney.display(receipt.summary.totalAmountFen))
        今日待补缴 \(OfflineCollectionMoney.display(receipt.summary.pendingAmountFen))
        """
        let alert = UIAlertController(title: "登记成功", message: message, preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "继续登记", style: .default) { [weak self] _ in
            self?.viewModel.startAnotherRegistration()
            self?.amountField.becomeFirstResponder()
        })
        alert.addAction(UIAlertAction(title: "查看今日明细", style: .default) { [weak self] _ in
            guard let self else { return }
            let controller = OfflineCollectionDailyViewController(
                businessDate: receipt.summary.businessDate,
                context: self.viewModel.context,
                service: self.viewModel.service
            )
            self.navigationController?.pushViewController(controller, animated: true)
        })
        present(alert, animated: true)
    }

    private func makeTitleLabel(_ text: String) -> UILabel {
        let label = UILabel()
        label.text = text
        label.font = .systemFont(ofSize: 16, weight: .semibold)
        label.textColor = AppColor.textPrimary
        return label
    }

    private func configureCard(_ card: UIView) {
        card.backgroundColor = .white
        card.layer.cornerRadius = AppRadius.lg
    }

    @objc private func amountChanged() {
        viewModel.updateAmount(amountField.text ?? "")
    }

    @objc private func methodTapped(_ sender: OfflinePaymentMethodButton) {
        viewModel.selectPaymentMethod(sender.method)
    }

    @objc private func submitTapped() {
        Task { await viewModel.submit() }
    }
}

extension OfflineCollectionRegistrationViewController: UITextFieldDelegate {
    func textField(
        _ textField: UITextField,
        shouldChangeCharactersIn range: NSRange,
        replacementString string: String
    ) -> Bool {
        guard let current = textField.text,
              let textRange = Range(range, in: current) else { return false }
        let next = current.replacingCharacters(in: textRange, with: string)
        return OfflineCollectionMoney.acceptsEditingText(next)
    }
}

/// 登记页的收款方式单选按钮。
final class OfflinePaymentMethodButton: UIControl {
    let method: OfflineCollectionPaymentMethod

    private let iconView = UIImageView()
    private let titleLabel = UILabel()

    /// 使用指定收款方式创建单选按钮。
    init(method: OfflineCollectionPaymentMethod) {
        self.method = method
        super.init(frame: .zero)
        setupUI()
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    /// 更新选中态视觉。
    func setSelected(_ selected: Bool) {
        isSelected = selected
        backgroundColor = selected ? UIColor(hex: 0xEEF5FF) : AppColor.inputBackground
        layer.borderColor = (selected ? AppColor.primary : UIColor.clear).cgColor
        layer.borderWidth = selected ? 1.5 : 0
        titleLabel.textColor = selected ? AppColor.primary : AppColor.textSecondary
    }

    private func setupUI() {
        layer.cornerRadius = AppRadius.md
        clipsToBounds = true
        accessibilityLabel = method.displayName

        iconView.image = UIImage(named: method.assetName)?.withRenderingMode(.alwaysOriginal)
        iconView.contentMode = .scaleAspectFit
        titleLabel.text = method.displayName
        titleLabel.font = .systemFont(ofSize: 14, weight: .medium)
        titleLabel.textAlignment = .center

        let stack = UIStackView(arrangedSubviews: [iconView, titleLabel])
        stack.axis = .vertical
        stack.alignment = .center
        stack.spacing = 5
        stack.isUserInteractionEnabled = false
        addSubview(stack)
        stack.snp.makeConstraints { make in
            make.center.equalToSuperview()
        }
        iconView.snp.makeConstraints { make in
            make.width.height.equalTo(22)
        }
        setSelected(false)
    }
}